It is known, to improve the physical properties of the rubbers used in tire construction in particular, to modify these in the most diverse manner, for example by introduction of particular end groups or by modification of the internal build-up of the polymer molecules. By modification of the polymers, for example by introduction of particular end groups, the physical properties, for example the rolling resistance or the wet skid properties, are said to be improved, as mentioned, in order to lower the fuel costs of cars and to increase their safety, in particular in the wet. Furthermore, bonding of the rubbers to be employed in tire construction to the fillers used there, in particular to the light-colored fillers, such as silica, should be improved substantially, so that a firm bond arises between the rubber matrix and the filler. The processing of such polymers or rubbers, in particular those to which light-colored fillers have been added, in the corresponding processing machines is furthermore said to be improved by the introduction of particular functional groups into the polymer molecules. British Patent Application GB 2 117 778-A and European Patent Application 0 180 853 A describe methods for the modification of unsaturated polymers with, for example, aromatic ketones or particular aminoaldehydes or aminoketones. By introduction of appropriate end groups into the unsaturated polymers, a good balance between rolling resistance and wet skid resistance in the tire rubber is achieved.
European Patent Application EP 0 767 179 A2 describes a process for the preparation of rubber mixtures which are modified in the end group by particular organosilicon compounds. A better bonding of the rubbers to the fillers comprising silica is said to be effected by the end group modification of the corresponding rubbers.
As has been found in our own experiments, the organosilicon compounds described in the European Patent Application mentioned, which are said to be for modification of the rubbers, are not so stable that they could withstand an attack by polymer anions. This means that the organosilicon compounds employed according to the European Patent Application for the modification of the rubbers lead not only to an end group modification of the rubbers but also to a high degree to undesirable multiple coupling reactions of the polymer anions present.